[PATCH v1 6/8] drm/i915/display: Add per-CRTC debugfs interface for CMRR fraction level

[Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>]

Add a per-CRTC debugfs entry 'vrr/cmrr_scaling' to allow reading and
writing the CMRR fraction level at runtime
for debug and testing purposes.

The file accepts three string values:
  "Low"     - Apply 1000/1001 fractional multiplier to vtotal
  "Default" - Use nominal fixed refresh rate vtotal as-is
  "High"    - Apply 1001/1000 fractional multiplier to vtotal

Signed-off-by: Mitul Golani <mitulkumar.ajitkumar.golani@intel.com>
---
 .../drm/i915/display/intel_display_debugfs.c  |  2 +
 drivers/gpu/drm/i915/display/intel_vrr.c      | 85 +++++++++++++++++++
 drivers/gpu/drm/i915/display/intel_vrr.h      |  1 +
 3 files changed, 88 insertions(+)

diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
index 81bef000a4e3..ae698560f306 100644
--- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
+++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
@@ -48,6 +48,7 @@
 #include "intel_psr.h"
 #include "intel_psr_regs.h"
 #include "intel_vdsc.h"
+#include "intel_vrr.h"
 #include "intel_wm.h"
 #include "intel_tc.h"
 
@@ -1387,6 +1388,7 @@ void intel_crtc_debugfs_add(struct intel_crtc *crtc)
 	intel_drrs_crtc_debugfs_add(crtc);
 	intel_fbc_crtc_debugfs_add(crtc);
 	hsw_ips_crtc_debugfs_add(crtc);
+	intel_vrr_crtc_debugfs_add(crtc);
 
 	debugfs_create_file("i915_current_bpc", 0444, root, crtc,
 			    &i915_current_bpc_fops);
diff --git a/drivers/gpu/drm/i915/display/intel_vrr.c b/drivers/gpu/drm/i915/display/intel_vrr.c
index bbc68c614667..e31778367245 100644
--- a/drivers/gpu/drm/i915/display/intel_vrr.c
+++ b/drivers/gpu/drm/i915/display/intel_vrr.c
@@ -20,6 +20,8 @@
 #include "skl_prefill.h"
 #include "skl_watermark.h"
 
+#include "linux/debugfs.h"
+
 #define FIXED_POINT_PRECISION		100
 #define CMRR_PRECISION_TOLERANCE	10
 
@@ -1227,3 +1229,86 @@ char *intel_vrr_cmrr_level_to_string(enum cmrr_level level)
 		return "Default";
 	}
 }
+
+static int string_to_cmrr(const char *str, enum cmrr_level *level)
+{
+	if (sysfs_streq(str, "Low"))
+		*level = CMRR_LOW;
+	else if (sysfs_streq(str, "High"))
+		*level = CMRR_HIGH;
+	else if (sysfs_streq(str, "Default"))
+		*level = CMRR_DEFAULT;
+	else
+		return -EINVAL;
+
+	return 0;
+}
+
+static ssize_t cmrr_write(struct file *file,
+			  const char __user *buf,
+			  size_t count, loff_t *ppos)
+{
+	struct seq_file *s = file->private_data;
+	struct intel_crtc *crtc = s->private;
+	struct intel_crtc_state *crtc_state =
+		to_intel_crtc_state(crtc->base.state);
+	char kbuf[32];
+	enum cmrr_level level;
+	int ret;
+
+	if (count >= sizeof(kbuf))
+		return -EINVAL;
+
+	if (copy_from_user(kbuf, buf, count))
+		return -EFAULT;
+
+	kbuf[count] = '\0';
+
+	ret = string_to_cmrr(kbuf, &level);
+	if (ret)
+		return ret;
+
+	crtc_state->vrr.cmrr.level = level;
+
+	return count;
+}
+
+static int cmrr_show(struct seq_file *s, void *data)
+{
+	struct intel_crtc *crtc = s->private;
+	struct intel_crtc_state *crtc_state =
+		to_intel_crtc_state(crtc->base.state);
+
+	seq_printf(s, "%s\n", intel_vrr_cmrr_level_to_string(crtc_state->vrr.cmrr.level));
+
+	return 0;
+}
+
+static int cmrr_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, cmrr_show, inode->i_private);
+}
+
+static const struct file_operations cmrr_fops = {
+	.owner   = THIS_MODULE,
+	.open    = cmrr_open,
+	.read    = seq_read,
+	.write   = cmrr_write,
+	.llseek  = seq_lseek,
+	.release = single_release,
+};
+
+void intel_vrr_crtc_debugfs_add(struct intel_crtc *crtc)
+{
+	struct dentry *root = crtc->base.debugfs_entry;
+	struct dentry *dir;
+
+	if (!root)
+		return;
+
+	dir = debugfs_create_dir("vrr", root);
+	if (IS_ERR(dir))
+		pr_err("debugfs creation : %ld\n", PTR_ERR(dir));
+
+	debugfs_create_file("cmrr_scaling", 0600, dir, crtc, &cmrr_fops);
+}
diff --git a/drivers/gpu/drm/i915/display/intel_vrr.h b/drivers/gpu/drm/i915/display/intel_vrr.h
index 86707b8af2e3..9b52a0bf0e4f 100644
--- a/drivers/gpu/drm/i915/display/intel_vrr.h
+++ b/drivers/gpu/drm/i915/display/intel_vrr.h
@@ -55,5 +55,6 @@ int intel_vrr_dcb_vmax_vblank_start_next(const struct intel_crtc_state *crtc_sta
 int intel_vrr_dcb_vmin_vblank_start_final(const struct intel_crtc_state *crtc_state);
 int intel_vrr_dcb_vmax_vblank_start_final(const struct intel_crtc_state *crtc_state);
 char *intel_vrr_cmrr_level_to_string(enum cmrr_level level);
+void intel_vrr_crtc_debugfs_add(struct intel_crtc *crtc);
 
 #endif /* __INTEL_VRR_H__ */
-- 
2.48.1